41.3. Data Values in PL/Tcl
The argument values supplied to a PL/Tcl function's code are simply the input arguments converted to text form (just as if they had been displayed by aSELECT statement). Conversely, thereturn command will accept any string that is acceptable input format for the function's declared return type. So, within the PL/Tcl function, all values are just text strings.